Optimization design of the impeller based on orthogonal test in an ultra-low specific speed magnetic drive pump

Abstract

To improve the hydraulic performance in an ultra-low specific speed magnetic drive pump, optimized design of impeller based on orthogonal test was carried out. Blades number Z, bias angle in peripheral direction of splitter blades θs, inlet diameter of splitter blades Dsi, and deflection angle of splitter blades α were selected as the main factors in orthogonal test. The credibility of the numerical simulation was verified by prototype experiments. Two optimized impellers were designed through the analysis of orthogonal test data. The internal flow field, pressure fluctuation, and radial force were analyzed and compared between optimized impellers and original impeller. The results reveal that impeller 7 (Z = 5, θs = 0.4θ, Dsi = 0.75D2, α = 0°) could increase the head and efficiency, compared to the original impeller, by 2.68% and 4.82%, respectively. Impeller 10 (Z = 5, θs = 0.4θ, Dsi = 0.55D2, α = 0°) reduced the head by 0.33% and increased the efficiency by 8.24%. At design flow rate condition, the internal flow of impeller 10 was the most stable. Peak-to-peak values of pressure fluctuation at the volute tongues of impeller 7 and impeller 10 were smaller than those of the original impeller at different flow rate conditions (0.6 Qd, 1.0 Qd and 1.5 Qd). Radial force distribution of impeller 10 was the most uniform, and the radial force variance of impeller 10 was the smallest.